A phosphate enriched manure fertilizer is prepared by reaction of manure with an acid phosphate reactant comprising phosphoric acid such as orthophosphoric acid and an acid phosphate salt such as and particularly monopotassium acid phosphate.
In particular embodiments the invention further relates to the mineral supplementation of manure fertilizers by the addition of phosphate and by the addition of potassium.
In further embodiments of the invention, the reaction of phosphoric acid with manure is continued at elevated temperatures and for a prolonged period and in the presence of a buffering quantity of alkali metal acid phosphate salt, effecting hydrolysis of the protein content of the manure and the generation of free amino acids.
The invention further relates to method for production of phosphate enriched manure, potassium enriched manure, and free amino acid containing manure fertilizer products.